Steady increases in Chinese manufacturing coupled with the country's low environmental standards contribute to pollution in California, Oregon and Washington. China's nitrogen oxide and carbon monoxide gases attribute to at least one extra day of smog per year in Los Angeles, according to the study. The Chinese pollution reaching the West Coast exceeds federal ozone standards, according to Bloomberg.

But China isn't the only culprit. Of China's export-related emissions, 21% are connected to U.S. exports.

“We’ve outsourced our manufacturing and much of our pollution, but some of it is blowing back across the Pacific to haunt us," said Steve Davis, a scientist at the University of California-Irvine and coauthor of the study "China’s International Trade and Air Pollution in the United States," published in the Proceedings of the National Academy of Sciences. "Given the complaints about how Chinese pollution is corrupting other countries’ air, this paper shows that there may be plenty of blame to go around.”

It takes six days for Chinese pollution to travel across the Pacific and reach American shores, meaning that the toxins created from the production of iPhones and other gadgets in China could reach the West Coast before the actual products. As much as 24% of the sulfate on the West Coast, which forms acid rain, can be tied to Chinese emissions, per the study. It is the first to quantify China's pollution on the West Coast.

Although the gases known as "westerlies" harm air quality on the West Coast, China's contribution is still small compared to local pollution. American cars, buses and planes sum up the majority of California's pollution.

The one silver lining to the study: Increased Chinese manufacturing lowered East Coast production and indirectly improved its air quality.

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